Vertically vibrating diaphragm pulp screen



July 2, 1940. -J. R. DUNBAR VERTICALLY VIBRATING DIAPHRAGM PULP SCREEN Filed Nov. 21, 1956 3 Sheets-Sheet 1 INVENTOR 7 TToRNEYs July 2, 1940. J. R.- DUNBAR v VERTICALLY VIBRATIG DIPHRAGM PULP SCREEN s sheets-sheet 3' Fiied Nov. 21, 19:56

TORNEYS "Patented July 2, 1940 fvEnTICALL mvg DIAPHRAGM e a James` R. Dunbar, Woodstock, NcWfBrunsWick,

Canada, assignmtol Thomas L.` Dunbar,` Mont-` real, Quebec,; Canada` `zapplication November '21, 1

936, serial nel 112,155"

` a. Thisinvention relatesgbroadly to improvements,

, incpulp screens and relates more particularly to flat screens in which the pulpstock is caused to iiow over slotted plates through which acceptable e stock passes, the `passage of stock being induced and `clogging of thescreens minimized orprevented` by the vibration of diaphragms" located below the screenplates. i i e Themechanismsat presentintgeneral useto vibrate the diaphragms are mechanically` driven againstthe action of heavy return springs and f therefore consume much;` power besides being subject `to rapid wear and requiringmuch lubrica- `section,illustrating the application of tion. In lmany such` devices the powerstroke l thrusts the `diaphragn'is `toward thelscreens and f thereverse `movement which induces stock flow through the screens is dependentlon the action of heavysprings with resultthat thespeed `and amplitude of downward movement cannot be r accurately controlled. y f d `The primary object of `my-inveritionisyto provide means for vibrating the diaphragms of` ilat pulp screens whichwill consume only-asmall amount of power `and lubricant and in `which g5 Wear `will be reduced to a negligible amount.` lA` further objectjistheprovision of a `dia-` phragm vibrating mechanism` in which the driviing power is ,directly` applied to effect downward aswell `as upward movement of thediaphragms, goed that the speed andamplitude ofbothrnovements will be accurately controlled. i e IAstill further object is `the provision. of a drive shown in Figure* 1.

scribedor disclosed inthe accompanying draw-fl' ings together `Vwith all, such modifications thereof and substitutions Vtherefor as are within `the solcpeof the appended claims. l e

In the drawings which illustrate ofneQembcdi-` ment` of the invention butto thedetails ofwhich the invention is not limited as are e possible 'and contemplat`ed Fig. `1,; is a front elevationpartly in `vertical tion to a flat pulp screen of conventional design.;

other modifications l my invern, l

Fig. 2 is an `end elevation ofthe "structure l v Fig. 3 is a `plan view ofthe diaphragm-vibrating mechanism.

Fig,` 4 is `a Vertical sectional view' of -oneof the hydraulic` actuating means of Figure 11 `on an.`

enlarged scale. r Fig. `5,1is`a vertical cross sectional Vview of the controlvalve `onthe line` 5 5 of Figure 3.

Referring more particularly to the drawings, II, designatesa screen boxor trough, thebottoirr l of which is formedlof a1 seriesrof exible Ydiasides of the trough mechanism otsimple,` durable and ,inexpensive` construction having .a `small ,number `of moving` partsof such character` and `arrangementfas to substantially eliminate the chance of accidental injury to an attendant., .l `Various `other objects and e invention may be ascertained from the following description and the` accompanying drawings. I

The invention consists essentially in the provision of hydraulic actuating `means for "each screen diaphragm," `the `said means" being con nected `in pairsbyrocking levers and the means of` each ,pairbeing hydraulically powered alterl nately in such wise thatlthe` hydraulic `power l `applied to `raise thescreendiaphragmassociated f with one means of the pair is applied through the rocking lever to positivelydepress the screen dia-` 50 pliragnrassociatedwith,l the other meanslofthe vided `and as many pairs of hydraulic actuating means as desired are connected to a single valve.

` In greater detail, the invention consists in the features 1:and cembinations ef `features herein dephragms I2 supported inthe usualway by `the. y `andby cross bearers I3 which` also support the slotted screen plates I4. The pulp stock to` be screened is` fed into the trough` above the plates I4, owsrthrough the plate` slots.

and is removed through thespace `betweenlthe plates anddiaphragmsfinlthe well known man-; ner. 'I'he lconstruction illustrated embodiesfsix diaphragms `but it will be` understood any even` number,` of `diaphragms may be used The boxie mounted on anyysuitable number of frames` I5 which are connectedfby a longitudinal beam I6 of suflicient rigidity toade'quately supportthe vi,

advantages of the pair(` `Any suitable typerof control valve` is pro-` loi-ating mechanism. The `central part of` eachl diaphragm I2 is clamped between: upper and lower plates I'I,`the` latter of which is rigidly ,connected to a depending push rod ,I8. l

`According `to this invention,.a seriesfof,` hy- `olraulic actuating means I9 aremounted "on, the

beam each centrallyunder a `diaphragm and operatively connectedto the push rod thereof.` The push `rodsare connected in pairs by rockinglevers 20 pil/'otallymounted midway between their-ends on vany suitable supports such as `brackets 2|.,.secured to and projecting upwardly from the beam I6.` `The connections between the push rods and rocking levers comprise` cross lpins 22 on the pushf v rods rotatable in blocks 23 slidably `engaging in slots 24 `inthe ends of .the rocking levers. While the arfzuatev movement ofthe lever ends is very slightand could be compensated for by providing slightly oversiz'eholes in the levers to receive the The hydraulic means designated by the nu` l merals- I9 to |96 may take a variety of forms but that now preferred consists of a series of dia-` phragm casings each comprising lower and upper annular lianges .and 26 respectively, between which a flexible diaphragm 21 is claimed by bolts 28 which'mayserve also to attach theflanges` to the beam I9. The lower flange 25 has connected to it a supply pipe 29. lThe upper ange is provided with an upstanding hollow neck 39 through which the lower end of av push rod 22 passes and is connected to the diaphragm 'by upper and lower clamping plates 3| rnountedon4 the push rod and secured by a nut 32. The neck is preferably provided with a bushing 33 of bronzeor other suitable material for engagement'with the push rod.` The space withineach neck above the diaphragmr may be lled with an elastic substance 34, such `as sponge rubber, ,to support the exposed portionof the diaphragm.`

. Forthe supply of a motive liquid under pressure to the casings'I tlf-|96 andfor the discharge of the liquid, there are provided a pair of supply mainsj35 and 36,.a pair of discharge mains' 31 and`38 and any suitable valvemechanisms for controlling the i'low of liquid in said mains and designated as' a whole by the numeral 99. Each ofy said mains is connected to every second casing of the series' by means of 'branches 4|] and 4I Vdirectly cross-connecting the supply and discharge mains and' to which the individual supply pipes 29 ofthe casings are connected'. Thus, the supply main 35 is directly cross-connected to the discharge main 3! by branches `49 to which the supply pipes 4of casings |9, I93 and I95 are connected. Similarly, thersupply main is cross-` connected directly vto the discharge main38 by thefbranches "4I to which the supply pipes of casings |92, I94 and |96 are connected. The two l` supply mains may be connected to a single inlet 42 through which they are supplied with liquid under pressure andthe two discharge mains may be connected to a singleloutlet 43.

" The 'valve mechanism comprises what is in realityavalve in each main andlany. suitable means for operating the valves in' predetermined relation'. As illustrated, thetwo supply valves are'. formed in'one and the Ytwo discharge valves in one andk all are enclosed in a single casing, but

` the arrangement maybefotherwise. The mecha-` nism illustrated comprises a valve casing 44l inserted inand common to all the supply and dischargemainsand containing a pair of rotatable valvemembers 45 and 49, pertaining respectively to the supply and `discharge mains and fixed on a shatyli provided with any suitable sort of drive means, such as a pulleyr48.

Thevalve member 45 is provided with a pair of diametrically disposed flow passages 49 and 59 arrangedfat right angles to one another and tially so, with the discharge passages 52 and 5|.

` The operation of the` device is as follows;

In the position illustrated, valve passage 49 is in alignment with supp-ly main 35 feeding casings i9', I93 and |95, while the valve passage 5I is at I right angles to and closes the discharge main 31 pertaining to these casings, so that uid under pressure is' admitted tobut cannot escape from these casings. The diaphragms in these casings and the push rodsconnected thereto are moved upwardly. At the same time, valve'passage 59 is at right angles rto supply main 35 feeding casings |92, |94 and |96, whilethe valve passage 52 and I9? is communicated through the rocking levers 29 to the push rods of casings' |92, I94 and I96 respectively and depresses the same so that liquid is expelled from these casings. Motive power is applied to rotate the'valve members 45 and 46 and, upon a quarter rotationof the valve members, the yconditions above described are reversed, namely, the valve passage 49 is at right angles to supply main 35, thus excluding fluid pressure from casings |92193 and I95,`while the valve passage 5I' is in alignment with the dis"A charge main draining these casings so that liquid previouslyv admitted may escape now. At the same time, valve passage 59 is in alignment with supply main 36 serving casings |92, |534 and |96` andvalve passage 5,2 is at right angles to the dis charge main 39 draining these casings, sothat fluidunder pressure is `admitted to but cannot `escape from these casings, 'The `pressure nowf forcesvupV the diaphragms'and push rods of casings I92, |94 and I96 and this movement is communicated through the rockinglevers `29 to depress the previously elevated push rods and diaphragmsof casings I9',A I93 and '|95 andexpel from them the liquid `previously admitted.` On

a4 further quarter rotation of the valve members the, condition first described is restored: By cona tinuously rotating the valvemembers liquid will' be lalternately admitted to vand released from each of the casings, thus causing reciprocating movement of the pushlrods and vibration of the screen diaphragms connected thereto.r

Asl the reciprocatingmovement of the push rods is only a fraction' of an-inch and as thev supply mains and other flow passages are fquite large relatively to the casings, there lis very little iiuid friction and very little actual flow of liquid. The system is constantly full of liquid and, as the flow necessary to accomplish each vibration of the diaphragms is only a' small fraction of the liquid in the system, the motive action is more one of intermittently applying pressure than of moving .the liquid body. This enables a very rapid vibration of the screen diaphragms to be realized. i

`The-rate of vibration is controlled by the rate of rotation of the valves. If desired,4 the discharge valves may be given a slight lead over the supply valves so that a cushioning effect lwill resultafter the manner well known in steam engine practice. This relative setting of the valves will also serve to llimit the amplitude of reciprocating rmovement of the push rods and diaphragms. .While the flow passages through the valves are illustrated as cylindrical andwhile there is shown considerable dead space at the circumference of the valves, it `will be understood 2,206,348 more or less than shown, according to the re-` sults desired, as will be Well understood by valve designers.

` While 'diaphragms are shown at the lower ends of the push rods,\it will be understood similar results will be obtained if the push rods constitute or are provided withpistons sliding in the `casings I9 to |96, but the `use of diaphragms is preferred as it avoids the mechanical friction incident to liquid tight lits between pistons and cylinders and thereby -reduces the power consumption if the device is served bya pump. The push rods are preferably easy runningfits in their bushings and therefore substantially frictionless.` An easy t is also desirable as it will leak and give notice if the associated diaphragm 2l should be rup tured.

Having thus described my invention, what I claim is: i

l. In a pulp screening machine, a series of screening diaphragms, a push rod connected to` each diaphragm, a iluid pressure actuated oper- `ating means for each push rod, rocking levers pivotally mounted intermediate adjacent push rods and operatively inter-connecting them and their associated operating means in pairs whereby the operating means of eachpair inuence one .another alternately and `means for alternately admitting liquid under pressure to and releas` ing liquid from each said operating means, the

i admission of liquid to `one operating means of each pairoccurring simultaneously with release `of liquid from the other means of each pair.

2. In a pulp screeningmachine, a series of screening diaphragms, a push rod connected to each diaphragm, a uidpressure actuated operat- "ing means for each push rod, means for admitting liquid under pressure `to alternate operating i `means of the series simultaneously and means operating coincidently with said admitting means for releasing liquid from the remaining means simultaneously and mechanical means interconnecting said push rods and their associated oper ating means in pairs and adapted upon actuation of one means of each pair by liquid under pressure "to reversely actuate the other means of each pair for expulsion `of liquid therefrom.

`3. In a pulp screening machine, a series of` screening diaphragms, a push rod connected to each diaphragm, pivotally mounted rocking levers pivotally connected to the push rods and connecting them in pairs, an operating chamber for each push rod in which the rod is reciprocatable, means for alternately admitting liquid under pressure to and releasing liquid from each said operating chamber for reciprocation of the push rods,` and flexible diaphragms connected between `the ends oi the push rods `and the walls of the respective operating chambers and constituting` ternately and for releasing liquid from saiddis` `between the push rod and chamber.

charge mains alternately, the release of liquid from `each discharge main being simultaneous with admission of liquid to the associated supply main,` and pivotally mounted rocking levers pivotally connected to the push rods and connecting the push rods associated with the rst supply main with the push rods associated with the second supply main.

5. In a pulp screening machine, a screening trough including screens and a row of diaphragms forming the bottom of said trough, a frame supporting the trough including a beam paralleling the row of diaphragms, a row of hydraulic chambers mounted on `said beam and severally aligned with the diaphragms, push rods connected to the diaphragms and slidably entering the hydraulic chambers, separate supply and discharge mains connected `to said hydraulic chambers, powered valve means for intermittently admitting liquid under pressure to a supply main and simultane- `ously releasing `liquid from an associated dis-` charge main, whereby each of said chambers is intermittently powered, brackets mounted on said beam, rocking levers pivotally mounted on said brackets and connected to adjacent push rods and operatively connecting the push rods in pairs whereby the admission of fluid to one chamber of each pair serves to expel fluid from the other chamber.

6. In a pulp screening machine, a series of I screening diaphragms, an hydraulic operatingchamber for each diaphragm, a push rod connected to each diaphragmand `having reciprocating engagement in the associated hydraulic chamber, a supply `main and a `discharge main, branches `directly connecting said mains together at intervals, pipes leading from said branches severally to 'alternate hydraulic chambers, a seca ond supply main and a second discharge main, branches directly` connecting said second mains together at intervals, pipes `leading from `said last mentioned branches severally to the remaining hydraulic chambers and valve means for admitting liquid under pressure to said supplymains alternately and for simultaneously releasing liquid from the associated discharge mains; and pivotally mounted rocking ,levers pivotally connected to the push rods and connecting the push rods` of said alternate chambers with the push rods of the remaining` chambers.

`7.111 a pulp screening machine, a pair of screening diaphragms, a single acting hydraulic chamber associated with each diaphragm,l a push rod connected with each diaphragm and having reciprocating engagement in i the associated chamber, means for admitting liquid under pressure to the chambers alternately and for releas` ingliquid from the chambers alternately, the admission toeach chamber synchronizing with the release from the `other chamber, and a rocking lever pivotally mounter `intermediate of and vconnected to said push rods whereby the operation of `each push rod `by admission of liquid to the associated chamber serves to operate the other push rod forexpulsion fo liquid from the other chamber.

8. In combination with structure according to claim 'Ladiaphragm in each chamber operatively connected to the wall of the chamber and to the push rod therein and forming sealing means JAMES R. DUN'BAR. 

